A is the false statement. In shock, resuscitation is started immediately and in parallel with assessment: vascular access and fluid resuscitation begin at once, and imaging is done as rapid bedside studies (POCUS, portable CXR) rather than delaying resuscitation. The other statements match the sources: children receive a 10-20 mL/kg crystalloid bolus, and non-response to fluids should prompt thinking of other mechanisms (vasopressors/inotropes, classify the type of shock).